• Journal of the Semiconductor & Display Technology
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• v.22 no.4
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• pp.124-130
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• 2023

Recently, fan out wafer level packaging, which enables high integration, miniaturization, and low cost, is being rapidly applied in the semiconductor industry. In particular, FOWLP is attracting attention in the mobile and Internet of Things fields, and is recognized as a core technology that will lead to technological advancements such as 5G, self-driving cars, and artificial intelligence in the future. However, as chip density and package size within the package increase, FOWLP warpage is emerging as a major problem. These problems have a direct impact on the reliability and electrical performance of semiconductor products, and in particular, cause defects such as vacuum leakage in the manufacturing process or lack of focus in the photolithography process, so technical demands for solving them are increasing. In this paper, warpage simulation according to the thickness of FOWLP material was performed using finite element analysis. The thickness range was based on the history of similar packages, and as a factor causing warpage, the curing temperature of the materials undergoing the curing process was applied and the difference in deformation due to the difference in thermal expansion coefficient between materials was used. At this time, the stacking order was reflected to reproduce warpage behavior similar to reality. After performing finite element analysis, the influence of each variable on causing warpage was defined, and based on this, it was confirmed that warpage was controlled as intended through design modifications.

• Journal of Aerospace System Engineering
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• v.12 no.3
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• pp.64-69
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• 2018

The high-velocity electromagnetic forming (EMF) process is based on the Lorentz force and the energy of the magnetic field. The advantages of EMF include improved formability, wrinkle reduction, and non-contact forming. In this study, the electromagnetic-structural interlocking analysis was performed in order to analyze the moldability of aluminum pipe using electromagnetic molding. The magnetic flux density was decreased due to increasing electrical resistance as the temperature increased, and the stress-strain curve decreased. The higher the temperature, the lower the flow stress, increasing deformation.

• Applied Chemistry for Engineering
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• v.28 no.4
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• pp.432-436
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• 2017

Carbon blocks were prepared by compression molding process using the mixture of isotropic cokes and binder pitches, which were reformed with different ${\beta}$-resin contents from pyrolysis fuel oil. Physical and chemical properties and also thermal behavior of binder pitches were investigated through elemental analysis, FT-IR and thermogravimetric analysis, respectively. The adhesion of binder pitches to isotropic coke particles was evaluated from SEM images of the fracture surface of carbon blocks. From these results, it is shown that the adhesion between the cokes and binder was enhanced by increasing the ${\beta}$-resin content of binder pitches. The density of the carbon block after carbonization also increased from 1.325 to $1.383g/cm^3$ by increasing the ${\beta}$-resin content of binder pitches from 1.4 to 20.1%.

• Toxicological Research
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• v.29 no.2
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• pp.115-120
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• 2013

To investigate the effects of short-term exposure of beryllium on the human immune system, the proportion of T-lymphocytes such as CD3+, CD4+, CD8+, CD95, and NK cells, and the proportion of B cells and $TNF{\alpha}$ level in peripheral blood and immunoglobulins in the serum of 43 exposed workers and 34 healthy control subjects were studied. External exposure to beryllium was measured by atomic absorption spectrometer as recommended by the NIOSH analytical method 7300. T lymphocyte subpopulation analysis was carried out with flow cytometer. The working duration of exposed workers was less than 3 months and the mean ambient beryllium level was $3.4{\mu}g/m^3$, $112.3{\mu}g/m^3$, and $2.3{\mu}g/m^3$ in molding (furnace), deforming (grinding), and sorting processes, respectively (cited from Kim et al., 2008). However, ambient beryllium level after process change was non-detectable (< $0.1{\mu}g/m^3$). The number of T lymphocytes and the amount of immunoglobulins in the beryllium-exposed workers and control subjects were not significantly different, except for the total number of lymphocytes and CD95 (APO1/FAS). The total number of lymphocytes was higher in the beryllium-exposed individuals than in the healthy control subjects. Multiple logistic regression analysis showed lymphocytes to be affected by beryllium exposure (odd ratio = 7.293; p<0.001). These results show that short-term exposure to beryllium does not induce immune dysfunction but is probably associated with lymphocytes proliferation.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.23 no.2
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• pp.75-83
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• 2013

Objectives: This study was conducted to estimate quartz concentrations in the airborne respirable dust from concrete manufacturing industries and to compare performance of two analytical methods, direct on filter(DOF) and the transfer methods in the Fourier Transform Infrared Spectroscopy(FTIR). Methods: Total 36 area samples were collected from 8 concrete manufacturing industries. Each respirable dust sample was collected by a 25 mm cassette attached to a 10 mm Dorr-Oliver nylon cyclone. The quartz content was estimated using the intensity of the absorption peak of quartz at $799cm^{-1}$ by FTIR. Results: By the comparison of quartz content in respirable dust between the two methods, the results of using DOF method were higher than that of transfer method. And the result of quartz concentrations in respirable dust estimated by DOF method were mostly higher than those by transfer method. Statistically significant difference of quartz concentrations in respirable dust were not found in shakeout, input, loading and transporting processes by two methods. But quartz concentrations in the molding process had the statistically significant difference between DOF and transfer method. Conclusions: The results of the study is suggested that, it be needed to correct the influence of the interferences in order to establish the DOF method when interfering minerals have an effect on quantitative analysis of quartz in respirable dust by the direct on filter method with FTIR.

• Journal of Biosystems Engineering
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• v.43 no.2
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• pp.128-137
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• 2018

Purpose: This study was designed to elucidate the energy-utilization patterns for five methods of robo production. Methods: Robo (fried melon cake) was produced using five different methods, and the energy used for each unit operation was calculated using standard equations. The sensory attributes of the products were determined by panelists. Data were analyzed using descriptive analysis and analysis of variance at p < 0.05. Results: The energy demands for processing 2.84 kg of melon seed into robo (fried melon cake) using processes 1 (traditional method), 2, 3, 4, and 5 (improved methods) were 50,599.5, 21,793.6, 20,379.7, 21,842.9, and 20,429.3 kJ, respectively. These are equivalent to energy intensities of 1,7816.7, 7,673.8, 7,175.9, 7,691.2, and 7,193.4 kJ/kg, respectively. For the traditional process, the frying operation consumed the highest energy (21,412.0 kJ), and the mixing operation consumed the lowest energy (675.0 kJ). For the semi-mechanized processes, the molding operation consumed the highest energy (6,120.0 kJ), and the dry milling consumed the lowest energy (14.4 kJ). Conclusions: The energy-consumption patterns were functions of the type of unit operation, the technology involved in the operations, and the size of the equipment used in the whole processing operation. Robo produced via the milling of dried melon seed before oil expression was rated highest with regard to the aroma and taste quality, as well as the overall acceptability of the sensory evaluation, and required the lowest energy consumption. Full mechanization of the process line has potential for further reduction of the energy demand.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.418-423
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• 2018

Recently, research and development of high-value leisure vessels has been carried out in Korea to revitalize the marine leisure industry and tap into the global maritime leisure market. FRP composite materials, which have excellent physical properties and are available for the manufacture of light hulls, are used widely. One of the most important design technologies is to secure structural safety of leisure vessels made from FRP composite materials. In this study, the structural strength was assessed for the design of an 8-meter high-speed planing leisure boat made from FRP composite materials. The design loads to verify the structural safety were calculated according to the rules for the classification of high speed light craft (KR, 2015), and structural analysis was conducted using a finite element model composed of an isotropic shell element, which has equivalent bending rigidity with the FRP sandwich panel. The analysis results were compared with the results of the strength test for fabricated specimens, and all internal structural components are sufficiently satisfied with the structural strength.

• Journal of Conservation Science
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• v.31 no.4
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• pp.489-497
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• 2015

Iron sickle is tool used in various ways and have various form. It has agricultural feature as well as is used in weapon. Previous studies have been focused on features of farming tools. In this study, metallurgical analysis of iron sickles are introduced because examples of analysis for iron sickles is rare. Two sickles form Yeongi Jangjae-ri are investigated and compared to one sickle of Yeongi Songwon-ri. Three sickles have forging molding process and heat treatment process. No.1 sickle of Jangjae-ri have martensite of quenching. No.2 sickle of Jangjae-ri was undergone high temperature as compared with others. This show manufacturing technology of sickles from Jangjae-ri in over the Songwon-ri's.

• Journal of the Korean Applied Science and Technology
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• v.24 no.3
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• pp.278-286
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• 2007

As a part of enhancing the performance of wood-plastic composites (WPC), polypropylene (PP)/ nanoclay (NC)/ wood flour (WF) nanocomposites were prepared using melt blending and injection molding process to evaluate their thermal stability. Thermogravimetric analysis (TGA) was employed to investigate thermal degradation kinetics of the nanocomposites both dynamic and isothermal conditions. Dynamic scans of the TGA showed an increased thermal stability of the nanocomposites at moderate wood flour concentrations (up to 20 phr, percentage based on hundred percent resin) while it decreased with the addition of 30 phr wood flour. The activation energy $(E_a)$ of thermal degradation of nanocomposites increased when nanoclay was added and the concentration of wood flour increased. Different equations were used to evaluate isothermal degradation kinetics using the rate of thermal degradation of the composites, expressed as weight loss (%) from their isothermal TGA curves. Degradation occurred at faster rate in the initial stages of about 60 min., and then proceeded in a gradual manner. However, nanocomposites with wood flour of 30 phr heated at $300^{\circ}C$ showed a drastic difference in their degradation behavior, and reached almost a complete decomposition after 40 min. of the isothermal heating. The degree of decomposition was greater at higher temperatures, and the residual weight of isothermal degradation of nanocomposites greatly varied from about 10 to 90%, depending on isothermal temperatures. The isothermal degradation of nanocomposites also increased their thermal stability with the addition of 1 phr nanoclay and of wood flour up to 20 phr. But, the degradation of PP100/NC1/MAPP3/WF30 nanocomposites with 30 phr wood flour occurs at a faster rate compared to those of the others, indicating a decrease in their thermal stability.

• Informatization Policy
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• v.19 no.3
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• pp.19-35
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• 2012

As Internet users increasingly consume news through the Internet, Internet portals face criticism that they are quickening the softening of public news and molding public opinions. Some portals have started to provide newscast services that directly connect the press, not grouping news sources on their own standards. This study aims to clarify how news grouping models and newscast models are different in terms of news softening and agenda setting. Specifically, authors conduct a content analysis on time-specific news content provided by top three portals-Naver, Daum, and Nate. By doing so, this study examines characteristics of news service models of Internet portals and their social and political implications. According to our study, the softening and tabloidization of portal news had not been improved even after adopting the newscast model. Therefore, portal journalism should be reorganized as a way to circulate healthy and qualified news content.